Method and system for water based phenolic binders for silicon-dominant anodes

ABSTRACT

Systems and methods for water based phenolic binders for silicon-dominant anodes may include an electrode coating layer on a current collector, where the electrode coating layer is formed from silicon and a pyrolyzed water-based phenolic binder. The water-based phenolic binder may include phenolic/resol type polymers crosslinked with poly(methyl vinyl ether-alt-maleic anhydride), poly(methyl vinyl ether-alt-maleic acid), and/or Poly(acrylamide-co-diallyldimethylammonium chloride) (PDADAM). The electrode coating layer may further include conductive additives. The current collector may comprise one or more of a copper, tungsten, stainless steel, and nickel foil in electrical contact with the electrode coating layer. The electrode coating layer may include more than 70% silicon. The electrode may be in electrical and physical contact with an electrolyte, where the electrolyte includes a liquid, solid, or gel. The battery electrode may be in a lithium ion battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims the benefit of U.S.application Ser. No. 16/925,111 filed Jul. 9, 2020, pending (nowallowed). The entirety of the above referenced application is herebyincorporated by reference.

FIELD

Aspects of the present disclosure relate to energy generation andstorage. More specifically, certain embodiments of the disclosure relateto a method and system for water based phenolic binders forsilicon-dominant anodes.

BACKGROUND

Conventional approaches for battery electrodes may be costly and causeelectrode coating layers to lose contact with the electrode.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present disclosureas set forth in the remainder of the present application with referenceto the drawings.

BRIEF SUMMARY

A system and/or method for using modified phenolic/resol type polymerswhich are water-soluble as binders for silicon anodes in Li-ion batteryelectrodes, substantially as shown in and/or described in connectionwith at least one of the figures, as set forth more completely in theclaims.

These and other advantages, aspects and novel features of the presentdisclosure, as well as details of an illustrated embodiment thereof,will be more fully understood from the following description anddrawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A and 1B are diagrams of a battery, in accordance with an exampleembodiment of the disclosure. FIG. 1A is a simplified example batteryand FIG. 1B shows realistic battery structures.

FIG. 2 illustrates exemplary materials for combining with phenolicresins to make water soluble derivatives, in accordance with an exampleembodiment of the disclosure.

FIG. 3A is a flow diagram of a direct coating process for fabricating acell with a silicon-dominant electrode, in accordance with an exampleembodiment of the disclosure.

FIG. 3B is a flow diagram for of an alternative process for laminationof electrodes, in accordance with an example embodiment of thedisclosure.

FIGS. 4A-4C illustrate thermal gravimetric analysis (TGA) of a driedphenolic resin and phenolic resins with varying amount of PMVMA, inaccordance with an example embodiment of the disclosure. FIG. 4A showsresults for phenolic resin alone. FIG. 4B shows analysis of a phenolicresin-PMVMA polymer blend at 1:1 ratio.

FIG. 4C shows analysis of a phenolic resin-PMVMA polymer blend at 1:0.25ratio.

FIG. 5 is a plot comparing the normalized capacity retention of a cellwith standard bonded anodes prepared using organic solvent versus a cellwith anodes prepared using a phenolic resin-PMVMA polymer blend, inaccordance with an example embodiment of the disclosure.

FIG. 6 is a plot comparing the normalized capacity retention of a cellwith standard bonded anodes prepared using organic solvent versus a cellwith anodes prepared using a phenolic resin-PMVMA-acid binder, inaccordance with an example embodiment of the disclosure.

FIG. 7 is a photo illustrating an anode adhesion test, in accordancewith an example embodiment of the disclosure.

FIG. 8 is a plot comparing the normalized capacity retention of a cellwith standard bonded anodes prepared using organic solvent versus a cellwith anodes prepared using phenolic/resol type polymer mixed withPDADAM, in accordance with an example embodiment of the disclosure.

DETAILED DESCRIPTION

FIG. 1 is a diagram of a battery with silicon-dominant anodes, inaccordance with an example embodiment of the disclosure. Referring toFIG. 1 , there is shown a battery 100 comprising a separator 103sandwiched between an anode 101 and a cathode 105, with currentcollectors 107A and 107B. There is also shown a load 109 coupled to thebattery 100 illustrating instances when the battery 100 is in dischargemode. In this disclosure, the term “battery” may be used to indicate asingle electrochemical cell, a plurality of electrochemical cells formedinto a module, and/or a plurality of modules formed into a pack.Furthermore, the cell shown in FIG. 1 is a very simplified examplemerely to show the principle of operation of a lithium ion cell.Examples of realistic structures are shown to the right in FIG. 1 ,where stacks of electrodes and separators are utilized, with electrodecoatings typically on both sides of the current collectors. The stacksmay be formed into different shapes, such as a coin cell, cylindricalcell, or prismatic cell, for example.

The development of portable electronic devices and electrification oftransportation drive the need for high performance electrochemicalenergy storage. Small-scale (<100 Wh) to large-scale (>10 KWh) devicesprimarily use lithium-ion (Li-ion) batteries over other rechargeablebattery chemistries due to their high-performance.

The anode 101 and cathode 105, along with the current collectors 107Aand 107B, may comprise the electrodes, which may comprise plates orfilms within, or containing, an electrolyte material, where the platesmay provide a physical barrier for containing the electrolyte as well asa conductive contact to external structures. In other embodiments, theanode/cathode plates are immersed in electrolyte while an outer casingprovides electrolyte containment. The anode 101 and cathode areelectrically coupled to the current collectors 107A and 1078, whichcomprise metal or other conductive material for providing electricalcontact to the electrodes as well as physical support for the electrodecoating layer in forming electrodes.

The configuration shown in FIG. 1 illustrates the battery 100 indischarge mode, whereas in a charging configuration, the load 109 may bereplaced with a charger to reverse the process. In one class ofbatteries, the separator 103 is generally a film material, made of anelectrically insulating polymer, for example, that prevents electronsfrom flowing from anode 101 to cathode 105, or vice versa, while beingporous enough to allow ions to pass through the separator 103.Typically, the separator 103, cathode 105, and anode 101 materials areindividually formed into sheets, films, or electrode coating layercoated foils. Sheets of the cathode, separator and anode aresubsequently stacked or rolled with the separator 103 separating thecathode 105 and anode 101 to form the battery 100. In some embodiments,the separator 103 is a sheet and generally utilizes winding methods andstacking in its manufacture. In these methods, the anodes, cathodes, andcurrent collectors (e.g., electrodes) may comprise films.

In an example scenario, the battery 100 may comprise a solid, liquid, orgel electrolyte. The separator 103 preferably does not dissolve intypical battery electrolytes such as compositions that may comprise:Ethylene Carbonate (EC), Fluoroethylene Carbonate (FEC), F2EC, VC,Propylene Carbonate (PC), Dimethyl Carbonate (DMC), Ethyl MethylCarbonate (EMC), Diethyl Carbonate (DEC), etc. with dissolved LiBF₄,LiAsF₆, LiPF₆, LiTFSI, LiFSI, LiDFOB, LiBOB, LiTDI, and LiClO₄ etc. Theseparator 103 may be wet or soaked with a liquid or gel electrolyte. Inaddition, in an example embodiment, the separator 103 does not meltbelow about 100 to 120° C., and exhibits sufficient mechanicalproperties for battery applications. A battery, in operation, canexperience expansion and contraction of the anode and/or the cathode. Inan example embodiment, the separator 103 can expand and contract by atleast about 5 to 10% without failing, and may also be flexible.

The separator 103 may be sufficiently porous so that ions can passthrough the separator once wet with, for example, a liquid or gelelectrolyte. Alternatively (or additionally), the separator may absorbthe electrolyte through a gelling or other process even withoutsignificant porosity. The porosity of the separator 103 is alsogenerally not too porous to allow the anode 101 and cathode 105 totransfer electrons through the separator 103.

The anode 101 and cathode 105 comprise electrodes for the battery 100,providing electrical connections to the device for transfer ofelectrical charge in charge and discharge states. The anode 101 maycomprise silicon, carbon, or combinations of these materials, forexample. Typical anode electrodes comprise a carbon material thatincludes a current collector such as a copper sheet. Carbon is oftenused because it has excellent electrochemical properties and is alsoelectrically conductive. Anode electrodes currently used in rechargeablelithium-ion cells typically have a specific capacity of approximately200 milliamp hours per gram. Graphite, the electrode coating layer usedin most lithium ion battery anodes, has a theoretical energy density of372 milliamp hours per gram (mAh/g). In comparison, silicon has a hightheoretical capacity of 4200 mAh/g. In order to increase volumetric andgravimetric energy density of lithium-ion batteries, silicon may be usedas the electrode coating layer for the cathode or anode. Silicon anodesmay be formed from silicon composites, with more than 50% silicon, forexample.

In an example scenario, the anode 101 and cathode 105 store the ion usedfor separation of charge, such as lithium. In this example, theelectrolyte carries positively charged lithium ions from the anode 101to the cathode 105 in discharge mode, as shown in FIG. 1 for example,and vice versa through the separator 105 in charge mode. The movement ofthe lithium ions creates free electrons in the anode 101 which creates acharge at the positive current collector 1078. The electrical currentthen flows from the current collector through the load 109 to thenegative current collector 107A. The separator 103 blocks the flow ofelectrons inside the battery 100, allows the flow of lithium ions, andprevents direct contact between the electrodes.

While the battery 100 is discharging and providing an electric current,the anode 101 releases lithium ions to the cathode 105 via the separator103, generating a flow of electrons from one side to the other via thecoupled load 109. When the battery is being charged, the oppositehappens where lithium ions are released by the cathode 105 and receivedby the anode 101.

The materials selected for the anode 101 and cathode 105 are importantfor the reliability and energy density possible for the battery 100. Theenergy, power, cost, and safety of current Li-ion batteries need to beimproved in order to, for example, compete with internal combustionengine (ICE) technology and allow for the widespread adoption ofelectric vehicles (EVs). High energy density, high power density, andimproved safety of lithium-ion batteries are achieved with thedevelopment of high-capacity and high-voltage cathodes, high-capacityanodes and functionally non-flammable electrolytes with high voltagestability and interfacial compatibility with electrodes. In addition,materials with low toxicity are beneficial as battery materials toreduce process cost and promote consumer safety.

The performance of electrochemical electrodes, while dependent on manyfactors, is largely dependent on the robustness of electrical contactbetween electrode particles, as well as between the current collectorand the electrode particles. The electrical conductivity of siliconanode electrodes may be manipulated by incorporating conductiveadditives with different morphological properties. Carbon black(SuperP), vapor grown carbon fibers (VGCF), and a mixture of the twohave previously been incorporated separately into the anode electroderesulting in improved performance of the anode. The synergisticinteractions between the two carbon materials may facilitate electricalcontact throughout the large volume changes of the silicon anode duringcharge and discharge.

State-of-the-art lithium-ion batteries typically employ agraphite-dominant anode as an intercalation material for lithium. Withdemand for lithium-ion battery performance improvements such as higherenergy density and fast-charging, silicon is being added as an electrodecoating layer or even completely replacing graphite as a dominant anodematerial. Most electrodes that are considered “silicon anodes” in theindustry are graphite anodes with silicon added in small quantities(typically <20%). These graphite-silicon mixture anodes must utilize thegraphite, which has a lower lithiation voltage compared to silicon; thesilicon has to be nearly fully lithiated in order to utilize thegraphite. Therefore, these electrodes do not have the advantage of asilicon or silicon composite anode where the voltage of the electrode issubstantially above OV vs Li/Li+ and thus are less susceptible tolithium plating. Furthermore, these electrodes can have significantlyhigher excess capacity on the silicon versus the opposite electrode tofurther increase the robustness to high rates. Lithium-ion batterieswith silicon-dominant anodes show much higher rate performance comparedto graphite anodes, with ˜10 C charge rates possible.

Silicon-based anodes have a lithiation/delithiation voltage plateau atabout 0.3-0.4V vs. Li/Li⁺, which allows it to maintain an open circuitpotential that avoids undesirable Li plating and dendrite formation.While silicon shows excellent electrochemical activity, achieving astable cycle life for silicon-based anodes is challenging due tosilicon's large volume changes during lithiation and delithiation.Silicon regions may lose electrical contact from the anode as largevolume changes coupled with its low electrical conductivity separate thesilicon from surrounding materials in the anode.

In addition, the large silicon volume changes exacerbate solidelectrolyte interphase (SEI) formation, which can further lead toelectrical isolation and, thus, capacity loss. Expansion and shrinkageof silicon particles upon charge-discharge cycling causes pulverizationof silicon particles, which increases their specific surface area. Asthe silicon surface area changes and increases during cycling, SEIrepeatedly breaks apart and reforms. The SEI thus continually builds uparound the pulverizing silicon regions during cycling into a thickelectronic and ionic insulating layer. This accumulating SEI increasesthe impedance of the electrode and reduces the electrode electrochemicalreactivity, which is detrimental to cycle life.

Although there has been a significant amount of effort to developsilicon anodes, the primary focus of developing these anodes is indealing with the following three key issues: 1) siliconnanoparticles—the majority of the silicon-based anodes that have highsilicon content use silicon nanoparticles to alleviate the large volumeexpansion. Nano-silicon is expensive and generally requires specialprocessing methods to prepare in large scale, which are not costeffective for large scale battery manufacturing. 2) Carbonadditives—silicon-based electrode manufacturers commonly use carbonadditives and binders mixed in organic solvents. The use of organicbased binders and solvents has challenges associated with the toxicityand high cost. 3) non-conducting binder material—the final anodeformulation still contains non conducting polymeric binder that does notcontribute to the electrochemical performance. As a result of this “deadweight” of the binder, the improvement of gravimetric energy density ofthe resulting cells may be limited.

Among the recent advancements in silicon-based anode development, one isthe direct coated anode using organic solvent-based binders followed byheat treatment to convert the binder into a carbon matrix. The presentdisclosure addresses the following key advancements: 1) the use ofenvironmentally friendly water-based anode processing and scalability;2) the capability of developing anodes with high Si content>90 wt. % forhigh capacity; 3) the development of Si dominant anodes free ofnon-conducting binders capable of fast charging (>2 C), i.e. anodes thatcontain only carbon and silicon; and 4) the development of a costeffective process, with silicon microparticles and water being used inthe anode production as opposed to solvents and silicon nanoparticles.Although solvent-based anodes have had some effectiveness in improvingcycle performance, these anodes may have weak adhesion to the currentcollector and contain non-continued carbon media that leads tounacceptable performance. Although the introduction of carbon additivescan somewhat improve the conductivity of the anode, the existence ofcarbon additives may weaken the adhesion of anode materials to thecurrent collector. Thus, the binder plays an important role in improvingthe performance of silicon anodes.

Currently, polymeric binders are used in almost all silicon anodetechnologies to keep the integrity of the anode during excessive volumechanges during lithiation. Although polyvinylidene difluoride (PVDF) iscommonly used in graphite cells, it is not capable of handling theexcessive volume changes of silicon. Additionally, PVDF is soluble onlyin toxic organic solvents such as NMP, which require solvent recoverysystems to recycle the solvent. In an example scenario, polymericbinders that are capable of mitigating the capacity fade of Si anodesoccurring at a high rate and long-term cycling are disclosed.Water-based anode fabrication is of interest for large scalemanufacturing of anodes to reduce the cost and eliminate the use oftoxic solvents. Objectives of a water-based anode polymer include: 1)ease of processing—the resin being highly soluble in water allowing forease of adjusting viscosity during coating; 2) high carbon yield andfilm-forming properties upon pyrolysis to create a conductive matrixaround and between silicon particles; 3) a homogeneous distribution ofpolymeric components in water and the slurry without phase separationduring the slurry formulation or coating; and 4) possessing a relativelylow pyrolysis temperature that is compatible with the thermal behaviorof the associated current collector.

Commercially available water-soluble polymers such as Poly(acrylic acid)(PAA) or Carboxymethyl cellulose (CMC), have significantly low carbonyield (<10 wt. %) and develop microcracks during pyrolysis. As a result,these water-soluble polymers exhibit poor mechanical properties in theanode after pyrolysis. Polymer resins and their derivatives with highcarbon yield upon pyrolysis are desired to yield a continuous carbonmedium while keeping the robustness of the anode. Although availablepolymers and their blends may be capable of achieving a high char yield,most of these polymers are insoluble in water.

Polymers are created from monomers and the molecular weight (MW) of apolymer is based on the identity of the monomer and the number ofmonomers present in the polymer molecule. Polymer molecular weights areusually given as averages and may fall in a distribution. The MWdistribution determines the properties of the polymer. In themeasurement of the average MW, the two most common ways to measure areMn, number averaged MW, and Mw, weight averaged MW (midpoint of thedistribution in terms of the number of molecules). Polydispersity of apolymer (Mw:Mn ratio) describes the distribution width. Other ways tocalculate MW include viscosity average molecular weight (Mv), and higheraverage molecular weight (Mz, Mz+1). The choice of method for polymermolecular weight determination depends on factors such as cost,experimental conditions and requirements. Degree of polymerization isalso often used in discussing polymers; this is the average number ofmonomeric units per molecule.

Among other polymer derivatives, phenolic resins are particularlyattractive since they have high molecular weight and high char yield,which are ideal properties for adoption as binders for silicon anodes.Phenolic resins (or phenol formaldehyde resins (PF)) include syntheticresins such as those obtained by the reaction of phenols withformaldehyde. Phenolic resins are divided into two main types, novolacsand resoles. Novolacs are phenol-formaldehyde resins made when the molarratio of formaldehyde to phenol is around one or less than one. Resolsare phenol-formaldehyde resins are made with a formaldehyde to phenolratio of greater than one (usually between about 1.2-2, in someembodiments, around 1.2-1.7). Ortho, meta and para linkages arecontemplated, as well as linear and branched structures. Phenolic resinscan have different molecular weights and degrees of polymerizationdepending on the reaction condition.

Novolac phenolic resins (may also be referred to as a phenolic/novolactype polymer) have phenolic units mainly linked by methylene groups. Anexample structure of a novolac phenolic resin is shown below (I):

In some embodiments, n may be >5; in other embodiments, n maybe >10, >50, >100, >500 or >1,000. Branched novolak types such asphenol-crotonaldehyde-resorcinol resins are also contemplated.

Resol phenolic resins (may also be referred to as a phenolic/resol typepolymer) may have methylene and/or ether bridges and have unreactedhydroxymethyl (—CH₂OH) groups. In some embodiments, the number of unitsin the resin may be >5; in other embodiments, the number of units maybe >10, >50, >100, >500 or >1,000. An example structure of a resolphenolic resin is shown below (II):

However, most phenolic resins typically do not readily dissolve in waterbut are soluble in alcohol and ketones. Some resol resins may beslightly soluble, but the solubility is generally low. Somewater-soluble phenols have very low water tolerance that leads to theformation of a separated polymer phase with the addition of water. Thisis an obstacle to water-based processing.

In the present disclosure, additives that overcome the low watersolubility obstacle associated with phenolic resins by increasing theirsolubility are described. Thus, in accordance with the disclosure,phenolic resins such as (I) or (II) above are modified in various ways,which significantly increases their solubility in water. The additivesmay react with the phenolic resin to make a derivative. In someembodiments, derivatives of the resins are made having but not limitedto —COOH, and/or —CO—NH₂ groups, etc. In other embodiments, otheradditives are combined with the phenolic resins to make blends. In someembodiments, the resol backbone can be used for further reactions tomake various binder structures. Depending on the specific derivatizationand/or blends that are created, water solubility (water tolerability)can be tailored to achieve desired binder properties required for Sianodes. In some embodiments, a phenolic/resol type polymer is used asthe starting material.

In this disclosure, a binder-free Si dominant (>70 wt. %, >50 wt. %)electrode is fabricated using water-soluble derivatives or blends ofphenolic polymer resins. The water soluble derivatives or blends ofphenolic polymer resins are created from different water-soluble polymercrosslinkers or additives, and are used as the binder. These water-basedslurries may possess high viscosity and result in high carbon yield uponheat treatment/pyrolysis while retaining the electrode structure. Thisis described further with respect to FIGS. 2-8 .

The phenolic resins can be derivatized by reacting, and/or can beincluded in a polymer blend by addition of polymer additives. Thephenolic resin derivatives have increased water solubility. FIG. 2illustrates some exemplary materials for combining with phenolic resinsto make derivatives or blends for use in making electrodes, inaccordance with an example embodiment of the disclosure.

One reaction used to derivatize the phenolic resins is crosslinking.Crosslinking is the process of forming chemical bonds to join (orbridge) two or more polymer chains. Crosslinking can occur when polymersare reacted, either internally, or with other compounds that havefunctional groups (crosslinking group). Crosslinking can occur bybridging with methyl, ethyl, ether, carboxylate, ester, amide, or anyother functional groups that can contribute to form a polymeric network.

One crosslinking group can be silanes and their combinations withdifferent functional groups. The functional groups and silane groups canplay a significant role of crosslinking within the phenolic resinpolymer matrix and as well as adhesion to the current collector.Referring to FIG. 2 , example silanes such asN-(3-(Trimethoxysilyl)propyl)ethylenediamine, methyl triacetoxysilane,and polydimethylsiloxane are shown. Other silanes having —OH, ester oramine groups are contemplated.

Phenolic type resins are also capable of crosslinking with water-solublepolymers containing hydrophilic functional groups to create a blend ofthe two polymers. The use of a water-soluble hydrophilic polymer cansignificantly improve the water tolerance and/or solubility of phenolicresin blend compared to unmodified phenolic resins.

Phenolic resin polymer blends can be made by the use of polymeradditives, including, but not limited to maleic anhydride and maleicacid polymers. FIG. 2 shows water soluble polymer additives such aspoly(methyl vinyl maleic anhydride) (PMVMA] and poly(methyl vinyl maleicacid)) (PMVMA-Acid). Polymer additives such as maleic anhydride polymersmay form blends which may be prepared with phenolic resins using wateras the solvent, for example, where poly(methyl vinyl maleic anhydride)(PMVMA) may be utilized in combination with phenolic resin. In anotherexample scenario, polymer blends may be prepared using maleic acid basedpolymers as the additive with water as the solvent, for example wherepoly(methyl vinyl maleic acid) (PMVMA-Acid) may be utilized incombination with phenolic resin.

As described herein and in copending U.S. case entitled “Silicon Anodeswith Water-Soluble Maleic Anhydride-, and/or Maleic Acid-ContainingPolymers/Copolymers, Derivatives, and/or combinations (with or withoutadditives) as Binders,” (Inventors Ji, L.; Ansari, Y.; Perera, S.; andPark, B., the entirety of which is hereby incorporated by reference,hydrophilic anhydride and/or acid containing polymers such aswater-soluble maleic anhydride- and/or maleic acid-containingpolymers/co-polymers, derivatives, and/or combinations can be used incombination with the disclosed phenolic/resol type polymers (phenolicresins). Maleic anhydride- and/or maleic acid-containing polymers may beused to crosslink phenolic/resol type polymers to make them watersoluble (or increase water solubility). As discussed herein, variouswater-soluble polymers can be used to derivatize phenolic/resol typepolymers to make a modified water soluble polymer that can be used as abinder for Si anodes. Water-soluble maleic anhydride- and/or maleicacid-containing polymers/co-polymers, derivatives, and/or combinationsmay be blended, crosslinked and/or derivatized to improve theirproperties. This includes being crosslinked to or co-polymerized withanother polymer, such as the phenolic resins disclosed herein. Theinclusion of a water-soluble polymer containing hydrophilic functionalgroups can significantly improve the water tolerance of a phenolic resinblend compared to unmodified phenolic resins. The polymer derivativescontaining hydrophilic functional groups used for crosslinking, blendingor co-polymerization may include anhydride and/or acid containingpolymers such as those disclosed in the copending U.S. case entitled“Silicon Anodes with Water-Soluble Maleic Anhydride-, and/or MaleicAcid-Containing Polymers/Copolymers, Derivatives, and/or combinations(with or without additives) as Binders.”

Other polymers can be used to create polymer blends with the phenolicresins. For example, acrylamide polymers can be used, including, but notlimited to poly(acrylamide-co-diallyldimethylammonium chloride)(PDADAM):

In some embodiments, x and/or y may be >10; in other embodiments, x andor y may be >100, >1,000, >10,000 or >100,000.

Additional polymers can be used to create polymer blends with thephenolic resins. For example, polyamide polymers can be used, including,but not limited to polyamide-imide (PAI):

In some embodiments, n may be >10; in other embodiments, n maybe >100, >1,000, >10,000 or >100,000.

Further derivatives of phenolic/resol type polymers includederivatization of the resol backbone by one or more functional groups tocreate a derivative. Derivatives include, but are not limited to ethers,polyethoxylates, esters, glycolipids, phosphates, oxiranes, and/orcarbamates. In some embodiments, the modification is at one or more ofthe phenolic oxygens. Example partial structures of derivatives areshown below, where A depicts the connection to the rest of the polymerstructure:

The as-synthesized phenolic polymer derivatives and/or blends may beused to prepare slurries using silicon and the as-synthesized phenolicpolymers as the binder, followed by doctor blade coating to preparesilicon-dominant anodes. The active material may be pyrolyzed under anargon atmosphere (or any inert atmosphere) to generate silicon-dominantanodes of 50% or greater silicon by weight. In accordance with thedisclosure, “active material” may comprise the active material alone, ormay encompass an entire electrode coating layer, which includes theactive material and other components.

In an example scenario, phenolic polymer resin may be cross-linked withvarious water soluble polymers to create derivatives (blends) that haveimproved water solubility and optimized viscosity, including: (1) maleicanhydride-polymers; (2) maleic acid-containing polymers; and (3)poly(acrylamide-co-diallyldimethylammonium chloride). These phenolicresin derivatives can be made into a slurry and used to create an anode,which is subsequently pyrolyzed. The pyrolyzed anodes show improvedadhesion to copper current collectors and desirable flexibility. Theresulting anodes are capable of fast charging and show similar or bettercycling performance compared to the current anode technology, which usesorganic solvents and lamination to a current collector for anodemanufacturing.

FIG. 3A is a flow diagram of a direct coating process for fabricating acell with a silicon-dominant electrode, in accordance with an exampleembodiment of the disclosure. This process comprises physically mixingthe electrode coating layer and conductive additive together, andcoating it directly on a current collector as opposed to forming theelectrode coating layer on a substrate and then laminating it on acurrent collector. This strategy may also be adopted by otheranode-based cells, such as graphite, conversion type anodes, such astransition metal oxides, transition metal phosphides, and other alloytype anodes, such as Sn, Sb, Al, P, etc.

In step 301, the raw electrode coating layer may be mixed in a slurrycomprising phenolic/resol type polymer (phenolic resin) with poly(methylvinyl ether-alt-maleic anhydride) (PMVMA) with the ratio of phenolicresin:PMVMA ranging but not limited to about 1:1, 1:0.5, and 1:0.25 byweight. The starting wt % of PMVMA may be about 10%, 20%, or <50% indeionized (DI) water. Phenolic resins and PMVMA form polymer blendsreadily with DI water without gelling/phase separation and creates aviscous solution that can be directly used for preparing the anodeslurry.

In another example scenario, phenolic/resol type polymer (phenolicresin) may be mixed with poly(methyl vinyl ether-alt-maleic acid)(PMVMA-Acid) with the ratio of phenolic resin:PMVMA-Acid ranging but notlimited to about 1:1, 1:0.5, and 1:0.25 by weight. The starting wt % ofPMVMA-Acid may be about 10%, 20%, or <50% in deionized (DI) water.

In yet another example scenario, phenolic/resol type polymer (phenolicresin) may be mixed with poly(acrylamide-co-diallyldimethylammoniumchloride) (PDADAM) with the ratio of phenolic resin:PDADAM ranging butnot limited to about 1:1, 1:0.5, and 1:0.25 by weight. The starting wt %of PDADAM can be about 10%, 20%, or <50% in deionized (DI) water. Ineach of these scenarios, no solvents are need in mixing the slurry.

The particle size (nano to micro) and mixing times may be varied toconfigure the electrode coating layer density and/or roughness.Furthermore, cathode electrode coating layers may be mixed in step 301,where the electrode coating layer may comprise lithium cobalt oxide(LCO), lithium iron phosphate, lithium nickel cobalt manganese oxide(NMC), Ni-rich lithium nickel cobalt aluminum oxide (NCA), lithiummanganese oxide (LMO), lithium nickel manganese spinel, LFP, Li-richlayer cathodes, LNMO or similar materials or combinations thereof, mixedwith carbon precursor and additive as described above for the anodeelectrode coating layer.

In step 303, the as-prepared slurry may be coated on a copper foil, 20μm thick in this example, and in step 305 may be dried at 130° C. in aconvection oven to dry the coating and form the green anode. Similarly,cathode electrode coating layers may be coated on a foil material, suchas aluminum, for example.

An optional calendering process may be utilized in step 307 where aseries of hard pressure rollers may be used to finish the film/substrateinto a smoother and denser sheet of material.

In step 309, the electrode coating layer may be pyrolyzed by heating to500-800° C., 650° C. in this example, in an inert atmosphere such thatcarbon precursors are partially or completely converted into conductivecarbon. The pyrolysis step may result in an anode electrode coatinglayer having silicon content greater than or equal to 50% by weight,where the anode has been subjected to heating at or above 400 degreesCelsius.

Pyrolysis can be done either in roll form or after punching in step 311.If done in roll form, the punching is done after the pyrolysis process.In instances where the current collector foil is notpre-punched/pre-perforated, the formed electrode may be perforated witha punching roller, for example. The punched electrodes may then besandwiched with a separator and electrolyte to form a cell. In step 313,the cell may be subjected to a formation process, comprising initialcharge and discharge steps to lithiate the anode, with some residuallithium remaining, and the cell capacity may be assessed. The fabricatedanode shows superior adhesion to copper, a remarkable cohesion, andexceptional flexibility. This anode is shown to be capable of fastcharging and performs similar or better than current anodes.

FIG. 3B is a flow diagram of an alternative process for lamination ofelectrodes, in accordance with an example embodiment of the disclosure.While the previous process to fabricate composite anodes employs adirect coating process, this process physically mixes the activematerial, conductive additive if desired, and binder together coupledwith peeling and lamination processes.

This process is shown in the flow diagram of FIG. 3B, starting with step321 where the raw electrode coating layer may be mixed in a slurrycomprising phenolic/resol type polymer (phenolic resin) with poly(methylvinyl ether-alt-maleic anhydride) (PMVMA) with the ratio of phenolicresin:PMVMA ranging but not limited to about 1:1, 1:0.5, and 1:0.25 byweight. The starting wt % of PMVMA may be about 10%, 20%, or <50% indeionized (DI) water. Phenolic resins and PMVMA form polymer blendsreadily with DI water without gelling/phase separation and creates aviscous solution that can be directly used for preparing the anodeslurry.

In another example scenario, phenolic/resol type polymers (phenolicresins) may be mixed with poly(methyl vinyl ether-alt-maleic acid)(PMVMA-Acid) with the ratio of Phenolic resin:PMVMA-Acid ranging but notlimited to about 1:1, 1:0.5, and 1:0.25 by weight (Table-2). Thestarting wt % of PMVMA-Acid may be about 10%, 20%, or <50% in deionized(DI) water.

In yet another example scenario, phenolic/resol type polymer (phenolicresins) may be mixed with poly(acrylamide-co-diallyldimethylammoniumchloride) (PDADAM) with the ratio of phenolic resin:PDADAM ranging butnot limited to about 1:1, 1:0.5, and 1:0.25 by weight. The starting wt %of PDADAM can be about 10%, 20%, or <50% in deionized (DI) water. Ineach of these scenarios, no solvents are need in mixing the slurry.

The particle size and mixing times may be varied to configure theelectrode coating layer density and/or roughness. Furthermore, cathodeelectrode coating layers may be mixed in step 321, where the electrodecoating layer may comprise lithium cobalt oxide (LCO), lithium ironphosphate, lithium nickel cobalt manganese oxide (NMC), Ni-rich lithiumnickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO),lithium nickel manganese spinel, LFP, Li-rich layer cathodes, LNMO orsimilar materials or combinations thereof, mixed with carbon precursorand additive as described above for the anode electrode coating layer.

In step 323, the slurry may be coated on a polymer substrate, such aspolyethylene terephthalate (PET), polypropylene (PP), or Mylar. Theslurry may be coated on the PET/PP/Mylar film at a loading of 3-6 mg/cm²for the anode and 15-35 mg/cm² for the cathode, and then dried in step325. An optional calendering process may be utilized where a series ofhard pressure rollers may be used to finish the film/substrate into asmoothed and denser sheet of material.

In step 327, the green film may then be removed from the PET, where theactive material may be peeled off the polymer substrate, the peelingprocess being optional for a polypropylene (PP) substrate, since PP canleave ˜2% char residue upon pyrolysis. The peeling may be followed by acure and pyrolysis step 329 where the film may be cut into sheets, andvacuum dried using a two-stage process (100-140° C. for 14-16 hours,200-240° C. for 4-6 hours). The dry film may be thermally treated at1000-1300° C. to convert the polymer matrix into carbon.

In step 331, the pyrolyzed material may be flat press or roll presslaminated on the current collector, where for aluminum foil for thecathode and copper foil for the anode may be pre-coated withpolyamide-imide with a nominal loading of 0.35-0.75 mg/cm² (applied as a5-7 wt % varnish in NMP, dried 10-20 hour at 100-140° C. under vacuum).In flat press lamination, the active material composite film may belaminated to the coated aluminum or copper using a heated hydraulicpress (30-70 seconds, 250-350° C., and 3000-5000 psi), thereby formingthe finished composite electrode. In another embodiment, the pyrolyzedmaterial may be roll-press laminated to the current collector.

In step 333, the electrodes may then be sandwiched with a separator andelectrolyte to form a cell. The cell may be subjected to a formationprocess, comprising initial charge and discharge steps to lithiate theanode, with some residual lithium remaining, and testing to assess cellperformance.

FIGS. 4A-4C illustrate thermal gravimetric analysis (TGA) of a driedunmodified phenolic/resol type polymers (phenolic resins) andPhenolic/resol type polymers (phenolic resins) which are blended withvarying amounts of Poly(methyl vinyl ether-alt-maleic anhydride)(PMVMA), in accordance with an example embodiment of the disclosure. Theratio of Phenolic resin:PMVMA ranges include but are not limited toabout 1:1, 1:0.5, and 1:0.25 by weight (Table-1). Starting wt % of PMVMAmay be about 10%, 20%, or <50% in deionized (DI) water.

TABLE 1 Sample-1 Sample-2 Sample-3 Phenolic/Resol PMVMA Phenolic/ResolPMVMA Phenolic/Resol PMVMA 1 1.000 1 0.500 1 0.250 Phenolic resin (g)5.1 Phenolic resin (g) 5.1 Phenolic resin (g) 5.1 PMVMA (g) 20.1 PMVMA(g) 10.05 PMVMA (g) 5.025

The analysis of the dried phenolic resin+PMVMA blends may be performedunder a nitrogen, argon, or any other inert atmosphere, or under forminggas atmosphere. The result of the TGA analysis indicates that the purephenolic resin has ˜65% char yield at 800° C., where the char yield maybe varied by changing the composition of PMVMA+phenolic resin blend.Even with 50% of phenolic resin replaced with PMVMA, as in Sample-1 ofFIG. 4B, the final polymeric blend displays 35-40% char yield after 700°C. pyrolysis under argon. Sample 3, shown in FIG. 4C, comprises aphenolic resin to PMVMA ratio of 1:0.25 with 50% wt % carbon yield at700° C. The photo insets in FIGS. 4B and 4C show samples of as-preparedwater-based phenolic resin-PMVMA binders.

FIG. 5 is a plot comparing the normalized capacity retention of a cellwith standard bonded anodes prepared using organic solvent versus a cellwith anodes prepared using the Phenolic resin-PMVMA polymer blend, inaccordance with an example embodiment of the disclosure. The anodes wereformed from slurries formulated to obtain a final anode composition withsilicon to carbon ratio of 90:10 W/W after pyrolysis. As shown in FIG. 5, the Phenolic resin-PMVMA polymer blend anode exhibits betternormalized capacity retention compared to the standard anode. In thisexample, the standard anode is a free-standing pyrolyzed anode that isbonded on to a copper current collector using a lamination process asopposed to the direct coated Phenolic resin-PMVMA polymer blend anode.

Further, phenolic/resol type polymers (phenolic resins) blended withvarying amounts of Poly(methyl vinyl ether-alt-maleic acid) (PMVMA-Acid)can be made in accordance with an example embodiment of the disclosure.The Phenolic resin:PMVMA-Acid ratio ranges include but are not limitedto about 1:1, 1:0.5, and 1:0.25 by weight (same as Table 1, above).Starting wt % of PMVMA-Acid can be about 10%, 20%, or <50% in deionized(DI) water. FIG. 6 is a plot comparing the normalized capacity retentionof a cell with standard bonded anodes prepared using organic solventversus a cell with anodes prepared using Phenolic resin-PMVMA-Acidbinder, in accordance with an example embodiment of the disclosure. Theanodes were formed from slurries formulated to obtain a final anodecomposition with a silicon to carbon ratio of 90:10 W/W after pyrolysis.As shown in FIG. 6 , the phenolic resin-PMVMA Acid anode exhibits betternormalized capacity retention compared to the standard anode, with about80% retention at nearly 200 cycles. In this example, the standard anodeis a free-standing pyrolyzed anode that is bonded on to a copper currentcollector using a lamination process as opposed to the direct coatedPhenolic resin-PMVMA Acid anode.

FIG. 7 is a photo illustrating an anode adhesion test, in accordancewith an example embodiment of the disclosure. The test setup includes aclamp 701 for holding an electrode 705 fastened to a glass slide 703using adhesive tape (not visible) holding the anode on one side on theother is a double sided adhesive tape (not visible) for coupling toweights.

The image demonstrates the result of an adhesion test for a pyrolyzedanode prepared using a phenolic resinPMVMA-acid blend. The anode shows asuperior adhesion strength, with the capability of holding greater than100 grams of weights before the coating detaches from the copper. Suchadhesion is much higher than most anodes which mostly fail to hold morethan 50 grams of weights. The improved adhesion of anodes may be due tothe presence of acid groups, which contribute to the retaining of theanode structure during the pyrolysis process and also due to the surfacetreatment effect of acidic groups on the metallic (e.g. copper) currentcollector.

Poly(acrylamide-co-diallyldimethylammonium chloride) (PDADAM) may becrosslinked with a phenolic/resol type polymer to prepare a new class ofwater-based phenol-PDADAM polymer blend as a binder for Si anodes. Inthis example, amide bonding enables water-based slurry preparation andimproves anode performance. In addition to the previous example ofcarboxylic groups, amides also may initiate crosslinking with phenolicresin in an aqueous medium. FIG. 8 is a plot comparing the normalizedcapacity retention of a cell with standard bonded anodes prepared usingorganic solvent versus a cell with anodes prepared using phenolic/resoltype polymer mixed with PDADAM, in accordance with an example embodimentof the disclosure.

The slurry may be formulated to obtain a final anode composition with asilicon to carbon ratio of 90:10 W/W after pyrolysis. The plot shows thecomparison of the normalized capacity retention of the standard anodesprepared using organic solvent versus anodes prepared using phenolicresin-PDADAM polymer. The phenolic resin-PDADAM anode exhibits abetter-normalized capacity retention compared to the standard anode. Thestandard anode is a free-standing pyrolyzed anode that is bonded on to acopper current collector using an adhesive coating.

In an example scenario, formaldehyde may be present in the phenolicresin used in anode active material slurry, where the degree of thepresence of formaldehyde in the phenolic resin may range from 1:0.5 to1:2 (phenol to formaldehyde) during synthesis. The synthesis of phenolicbinders may be tailored to optimize the water tolerance(solubility/dispersibility), solid content, and viscosity of thephenolic resin. The water tolerance of phenolic resin can be 10-80%w.r.t. phenolic resin content before a phase separation in water occurs.Phenolic resin may contain 1-10 wt %, 10-25 wt %, or 25-90 wt %. Theamount of binder resin required to achieve the desired carbon wt % afterpyrolysis is significantly lowered as the initial solid content and charyield of the phenolic resin-polymer conjugated resin is higher than thecommon water soluble polymer binders. The water solubility and viscosityof the phenolic resin may be configured to achieve desired slurryviscosity via crosslinking with one or more water soluble polymers. Inone embodiment, the water tolerance of a phenolic/resol type polymer canbe optimized during synthesis of the polymer, as described above.

In another example scenario, water-based phenolic resins may be createdby modification of a phenolic resin with another polymer, such as bycrosslinking. Phenolic resins crosslinked with poly(methyl vinylether-alt-maleic anhydride); poly(methyl vinyl ether-alt-maleic acid)and other derivatives of methyl vinyl ether-alt-maleic with differentmolecular weights and degree of polymerization may be used to formsilicon-dominant anodes without solvents. These polymer blends may beused with different molecular weights with functional aliphatic andaromatic amine compounds as binders for silicon-dominant anodes. Inaddition, any of the above-mentioned polymer components may be used withphenolic or resol type polymers for all different types of Si or SiO_(x)anodes.

In yet another example scenario, unmodified phenolic resins may beutilized without the aforementioned crosslinking polymers, theirderivatives, and their combinations for all different types of Si orSiO_(x) anodes. Furthermore, the crosslinked polymers, theirderivatives, and their combinations may be used without pyrolysis forelectrode preparation. The above phenolic resins also can be expanded touse with coated type Si/SiOx. Coating materials can be raging fromconductive carbon to ceramic coating. The final slurry prepared usingthe above may contain secondary electroactive/inactive components thatmay support the performance of the anode.

Conductive additives, such as Super P, carbon black, graphite, graphene,carbon nano/micro fibers, carbon nanotubes, porous (meso/macro) carbonsand other types of one-, two-, three-dimensional carbon materials can beintroduced into all different aforementioned crosslinking polymers,their derivatives, and their combinations. Similarly, metallicnano/micro particle, fibers, wires and other types of one-, two-,three-dimensional structures may be introduced into all differentaforementioned crosslinked polymers, their derivatives, and theircombinations. Finally, water soluble polyimides such as polyamide-imideand polyimide analogs (<50%) may be used in combination with phenolicresin to form silicon dominant anodes with improved performance. Theseanalogues can have different molecular weights and degree ofpolymerization.

Water based crosslinked phenolic resins with high char yield uponpyrolysis at temperatures>200 degC may be utilized as electrode binder.These polymer blends can undergo curing before pyrolysis to form are-arranged polymeric network. The preparation of polymers may comprisemany decomposable functional groups such as —OH, NH—, NH₂, —COOH at arelatively low temperature, below the decomposition temperature ofphenols. These groups can generate gaseous byproducts that can createnano to micro pores within the anode/carbon media. The presence of thesepores may facilitate the rapid volume changes of silicon microparticlesduring cycling as well as electrolyte soaking to improve ionicconductivity of the anodes.

Phenolic resins with poly(methyl vinyl ether-alt-maleic acid), whichcontains carboxylic acid groups, may be utilized in silicon-dominantanode fabrication. These carboxylicacid group materials maysignificantly improve the adhesion of anode materials on the currentcollector, such as a copper foil surface. The presence of carboxylicacid groups may participate in surface treatment/roughening of thecopper, or other metal, current collector. Additionally, thesefunctional groups may further improve the particle to particleinteractions required to retain the electrode structure duringpyrolysis.

The presence of functional groups such as —COOH and —NH₂ may promote thecrosslinking with the functional groups in phenolic polymer resin(various —OH and —O—). In addition, in-situ crosslinking via thermaland/or photochemical crosslinking of phenol or phenolic type polymerresins in the presence of a second water-soluble polymer may occur withthese materials. The crosslinking reaction may be initiated in thepresence of an inorganic salt or catalyst or photochemically.

Strong hydrogen bonds associated with —COOH groups may improve theparticle-particle affinity. The existence of strong chemical bonds inthe slurry form is utilized to create a carbon matrix that stronglyadheres to the particles. New bonds may be formed between particles andthe copper surface as a result of decomposition of these functionalgroups upon pyrolysis.

These materials and combinations may provide advantages such as beingenvironmentally friendly, increased cycle life, reduced cost, fasterprocessing, improved anode adhesion, and improved manufacturability.

In an example embodiment of the disclosure, a method and system aredescribed for water based phenolic binders for silicon-dominant anodes.The battery electrode may comprise an electrode coating layer on acurrent collector, where the electrode coating layer is formed fromsilicon and a pyrolyzed water-based phenolic binder. The water-basedphenolic binder may comprise poly(methyl vinyl ether-alt-maleicanhydride), poly(methyl vinyl ether-alt-maleic acid), and/or methylvinyl ether-alt-maleic. The water-based phenolic may be crosslinked witha phenolic resin. The electrode coating layer may comprise conductiveadditives. The current collector may comprise one or more of a copper,tungsten, stainless steel, and nickel foil in electrical contact withthe electrode coating layer. The electrode coating layer may comprisemore than 70% silicon. The electrode may be in electrical and physicalcontact with an electrolyte, where the electrolyte includes a liquid,solid, or gel. The battery electrode may be in a lithium ion battery.These binder systems can use with other type of electrochemical storagedevices, not limited to Li—S(lithium sulfur), Na-ion (sodium ion),Li-air (lithium-air).

As utilized herein, “and/or” means any one or more of the items in thelist joined by “and/or”. As an example, “x and/or y” means any elementof the three-element set {(x), (y), (x, y)}. In other words, “x and/ory” means “one or both of x and y”. As another example, “x, y, and/or z”means any element of the seven-element set {(x), (y), (z), (x, y), (x,z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means “one ormore of x, y and z”. As utilized herein, the term “exemplary” meansserving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “e.g.,” and “for example” set off lists ofone or more non-limiting examples, instances, or illustrations. Asutilized herein, a battery, circuitry or a device is “operable” toperform a function whenever the battery, circuitry or device comprisesthe necessary hardware and code (if any is necessary) or other elementsto perform the function, regardless of whether performance of thefunction is disabled or not enabled (e.g., by a user-configurablesetting, factory trim, configuration, etc.).

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

The invention claimed is:
 1. A method of forming an electrode, themethod comprising: creating an electrode coating layer from an electrodeslurry comprising an aqueous solution of a water-based phenolic binderand Si powder, with optional additives; fabricating a battery electrodeby coating the slurry on a current collector; and pyrolyzing saidelectrode coating layer; wherein the water-based phenolic bindercomprises a phenolic/resol type polymer crosslinked with poly(methylvinyl ether-alt-maleic anhydride).
 2. The method according to claim 1,wherein the electrode coating layer further comprises conductiveadditives.
 3. The method according to claim 1, wherein the currentcollector comprises one or more of a copper, tungsten, stainless steel,and nickel foil in electrical contact with the electrode coating layer.4. The method according to claim 1, wherein the electrode coating layercomprises more than 70% silicon.
 5. The method according to claim 1,wherein the electrode is in electrical and physical contact with anelectrolyte, the electrolyte comprising a liquid, solid, or gel.
 6. Amethod of forming an electrode, the method comprising: creating anelectrode coating layer from an electrode slurry comprising an aqueoussolution of a water-based phenolic binder and Si powder, with optionaladditives; fabricating a battery electrode by coating the slurry on acurrent collector; and pyrolyzing said electrode coating layer; whereinthe water-based phenolic binder comprises a phenolic/resol type polymercrosslinked with poly(methyl vinyl ether-alt-maleic acid).
 7. The methodaccording to claim 6, wherein the electrode coating layer furthercomprises conductive additives.
 8. The method according to claim 6,wherein the current collector comprises one or more of a copper,tungsten, stainless steel, and nickel foil in electrical contact withthe electrode coating layer.
 9. The method according to claim 6, whereinthe electrode coating layer comprises more than 70% silicon.
 10. Themethod according to claim 6, wherein the electrode is in electrical andphysical contact with an electrolyte, the electrolyte comprising aliquid, solid, or gel.
 11. A method of forming an electrode, the methodcomprising: creating an electrode coating layer from an electrode slurrycomprising an aqueous solution of a water-based phenolic binder and Sipowder, with optional additives; fabricating a battery electrode bycoating the slurry on a current collector; and pyrolyzing said electrodecoating layer; wherein the water-based phenolic binder comprises aphenolic/resol type polymer crosslinked withpoly(acrylamide-co-diallyldimethylammonium chloride) (PDADAM).
 12. Themethod according to claim 11, wherein the electrode coating layerfurther comprises conductive additives.
 13. The method according toclaim 11, wherein the current collector comprises one or more of acopper, tungsten, stainless steel, and nickel foil in electrical contactwith the electrode coating layer.
 14. The method according to claim 11,wherein the electrode coating layer comprises more than 70% silicon. 15.The method according to claim 11, wherein the electrode is in electricaland physical contact with an electrolyte, the electrolyte comprising aliquid, solid, or gel.
 16. A method of forming an electrode, the methodcomprising: creating an electrode coating layer from an electrode slurrycomprising an aqueous solution of a water-based phenolic binder and Sipowder, with optional additives; fabricating a battery electrode bycoating the slurry on a current collector; and pyrolyzing said electrodecoating layer; wherein the water-based phenolic binder comprises aphenol-crotonaldehyde-resorcinol derivative.
 17. The method according toclaim 16, wherein the electrode coating layer further comprisesconductive additives.
 18. The method according to claim 16, wherein thecurrent collector comprises one or more of a copper, tungsten, stainlesssteel, and nickel foil in electrical contact with the electrode coatinglayer.
 19. The method according to claim 16, wherein the electrodecoating layer comprises more than 70% silicon.
 20. The method accordingto claim 16, wherein the electrode is in electrical and physical contactwith an electrolyte, the electrolyte comprising a liquid, solid, or gel.21. A method of forming an electrode, the method comprising: creating anelectrode coating layer from an electrode slurry comprising an aqueoussolution of a water-based phenolic binder and Si powder, with optionaladditives; fabricating a battery electrode by coating the slurry on acurrent collector; and pyrolyzing said electrode coating layer; whereinthe water-based phenolic binder comprises a phenolic/resol type polymerderivatized by one or more functional groups selected from the groupconsisting of ethers, polyethoxylates, esters, glycolipids, phosphates,oxiranes, and/or carbamates.
 22. The method according to claim 21,wherein the electrode coating layer further comprises conductiveadditives.
 23. The method according to claim 21, wherein the currentcollector comprises one or more of a copper, tungsten, stainless steel,and nickel foil in electrical contact with the electrode coating layer.24. The method according to claim 21, wherein the electrode coatinglayer comprises more than 70% silicon.
 25. The method according to claim21, wherein the electrode is in electrical and physical contact with anelectrolyte, the electrolyte comprising a liquid, solid, or gel.